Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel and dice the sweet potato into uniform 1/2-inch cubes, and chop the broccoli and red bell pepper into bite-sized pieces.
Place the chicken breast on one side of the baking sheet and arrange the chopped vegetables in a single layer on the remaining space.
Drizzle the olive oil over the chicken and vegetables, then sprinkle evenly with dried rosemary, thyme, garlic powder, sea salt, and black pepper.
Toss the vegetables with your hands or a spatula to ensure they are well-coated in the oil and herbs, and flip the chicken to season both sides.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are fork-tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing it against the grain to maintain juiciness.
Plate the sliced chicken alongside the roasted vegetable medley and serve immediately while hot.